Propeller alignment devices

Abstract

A propeller alignment device is described. The propeller alignment device can include a second retainer attached to a propeller and a motor. The propeller alignment device can also include a first retainer that does not rotate, but that is aligned with the second retainer. The first retainer can include two or more magnets oppositely orientated relative to each other. The second retainer can also include two or more magnets oppositely orientated relative to each other. As the second retainer rotates relative to the first retainer, the magnets may alternatingly align with each other. In the absence of a current applied to the motor, the magnets may magnetically bias the second retainer into a predetermined orientation relative to the first retainer. The predetermined orientation can be predetermined to correspond to an alignment of the propeller that is desirable (e.g., that minimizes aerodynamic drag on the propeller).

What is claimed is: 
     
       1. An aerial vehicle, comprising:
 a frame; 
 a motor connected to the frame and comprising a shaft; 
 a propeller connected to the shaft such that rotation of the shaft by the motor causes the propeller to rotate; 
 a mounting housing connected to the frame; and 
 an alignment structure to align the propeller relative to the mounting housing, the alignment structure comprising:
 a stationary ring secured to the mounting housing, the stationary ring comprising:
 a top surface; 
 a first magnet disposed within a first area of the stationary ring and orientated with a first north pole extending towards the top surface; and 
 a second magnet disposed within a second area of the stationary ring and oriented with a first south pole extending towards the top surface; and 
 
 a rotating ring aligned with the stationary ring and configured to rotate relative to the stationary ring as the propeller is rotated by the motor, the rotating ring comprising:
 a mounting location configured to mate with the propeller; 
 a rotational axis extending through the rotating ring; 
 a bottom surface; 
 a third magnet disposed within a first area of the rotating ring and oriented with a second north pole extending towards the bottom surface; and 
 a fourth magnet disposed within a second area of the rotating ring and orientated with a second south pole extending towards the bottom surface, 
 
 
 wherein the first magnet and the second magnet are positioned on the stationary ring and the third magnet and the fourth magnet are positioned on the rotating ring such that the first magnet and the second magnet alternatingly align with the third magnet and the fourth magnet as the rotating ring rotates relative to the stationary ring, and wherein the first magnet, the second magnet, the third magnet, and the fourth magnet produce a force that causes the rotating ring to rotate about the rotational axis to a predetermined orientation, the first magnet being disposed below the fourth magnet and the second magnet being disposed below the third magnet when the rotating ring is in the predetermined orientation. 
 
     
     
       2. The aerial vehicle of  claim 1 , wherein the force resists an opposing rotational force applied to the propeller when the aerial vehicle is moving. 
     
     
       3. The aerial vehicle of  claim 1 , wherein the first area of the stationary ring comprises a first c-shaped half of the stationary ring, and the second area of the stationary ring comprises a second c-shaped half of the stationary ring. 
     
     
       4. The aerial vehicle of  claim 1 , wherein each of the first magnet, the second magnet, the third magnet, and the fourth magnet comprise a plurality of cylindrical magnets, each plurality of cylindrical magnets being disposed within the respective first and second areas of the stationary ring and the respective first and second areas of the rotating ring. 
     
     
       5. An alignment device, comprising:
 a motor comprising a rotor and a stator, the rotor configured to rotate relative to the stator about a rotation axis in response to a current applied to the motor; 
 a first retainer coupled to the stator, the first retainer comprising a plurality of stator magnets; 
 a first set of stator magnets of the plurality of stator magnets having north poles oriented in a first direction; 
 a second retainer spaced apart from the first retainer along the rotation axis and coupled to the rotor, the second retainer comprising a plurality of rotor magnets; and 
 a first set of rotor magnets of the plurality of rotor magnets having north poles oriented in a second direction that is opposite the first direction, 
 wherein, in the absence of the current applied to the motor, the first set of stator magnets and the first set of rotor magnets magnetically bias the rotor into a predetermined orientation about the rotation axis with respect to the stator. 
 
     
     
       6. The alignment device of  claim 5 , further comprising:
 a second set of stator magnets of the plurality of stator magnets having north poles oriented in the second direction; and 
 a second set of rotor magnets of the plurality of rotor magnets having north poles oriented in the first direction, 
 wherein in the absence of the current applied to the motor, the second set of stator magnets and the second set of rotor magnets magnetically bias the rotor into the predetermined orientation. 
 
     
     
       7. The alignment device of  claim 6 , wherein the first set of stator magnets and the second set of stator magnets are located in respective first and second portions of the first retainer and the first set of rotor magnets and the second set of rotor magnets are located in respective first and second portions of the second retainer, and wherein in the predetermined orientation the first portion of the first retainer is aligned with the first portion of the second retainer. 
     
     
       8. The alignment device of  claim 6 , wherein the first set of stator magnets and the second set of stator magnets are intermixed throughout the first retainer and the first set of rotor magnets and the second set of rotor magnets are intermixed throughout the second retainer. 
     
     
       9. The alignment device of  claim 8 , wherein the plurality of stator magnets are inserted into a first plurality of openings in the first retainer, and the plurality of rotor magnets are inserted into a second plurality of openings in the second retainer. 
     
     
       10. The alignment device of  claim 6 , wherein the first portion of the second retainer comprises a first half of the second retainer and the second portion comprises a second half of the second retainer. 
     
     
       11. The alignment device of  claim 5 , further comprising:
 a propeller coupled to the rotor, wherein the first set of stator magnets and the first set of rotor magnets magnetically bias the propeller into an orientation having reduced aerodynamic resistance. 
 
     
     
       12. The alignment device of  claim 11 , wherein the propeller is a lift propeller and the first set of stator magnets and the first set of rotor magnets magnetically bias the propeller into the orientation when the lift propeller is not in use. 
     
     
       13. The alignment device of  claim 5 , wherein the current applied to the motor is applied to one or more electromagnets of the stator. 
     
     
       14. The alignment device of  claim 5 , wherein the current applied to the motor is applied to one or more electromagnets of the rotor. 
     
     
       15. A motor system, comprising:
 a propeller; 
 a motor coupled to the propeller and comprising a rotor and a stator, the rotor and the propeller configured to rotate relative to the stator about a rotation axis in response to a current applied to the motor; 
 a first retainer coupled to the stator, the first retainer comprising a plurality of stator magnets; 
 a first set of stator magnets of the plurality of stator magnets having north poles oriented in a first direction; 
 a second retainer spaced apart from a first plate along the rotation axis and coupled to the rotor, the second retainer comprising a plurality of rotor magnets; and 
 a first set of rotor magnets of the plurality of rotor magnets having north poles oriented in a second direction that is opposite the first direction, 
 wherein, in the absence of the current applied to the motor, the first set of stator magnets and the first set of rotor magnets magnetically bias the propeller into a predetermined orientation about the rotation axis with respect to the stator. 
 
     
     
       16. The motor system of  claim 15 , further comprising:
 a sensor package configured to detect when the propeller is in the predetermined orientation; and 
 a processor configured to:
 receive sensing information from the sensor package; and 
 in response to receiving the sensing information, apply a first current to the motor to cause the propeller to rotate with respect to the stator. 
 
 
     
     
       17. The motor system of  claim 16 , wherein the processor is further configured to determine the first current based at least in part on the sensing information. 
     
     
       18. The motor system of  claim 15 , wherein, in the predetermined orientation, the propeller has a lower energy state compared to when the propeller is out of the predetermined orientation. 
     
     
       19. The motor system of  claim 15 , further comprising:
 a second set of stator magnets of the plurality of stator magnets having north poles oriented in the second direction; and 
 a second set of rotor magnets of the plurality of rotor magnets having north poles oriented in the first direction, 
 wherein in the absence of the current applied to the motor, the second set of stator magnets and the second set of rotor magnets magnetically bias the rotor into the predetermined orientation. 
 
     
     
       20. The motor system of  claim 19 , wherein the first set stator magnets and the second set of rotor magnets alternatingly align as the rotor rotates relative to the stator.